1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus. More particularly, aspects of the present invention relate to a toner path opening and closing apparatus having an improved structure to regulate the inflow and outflow of toner that is supplied to a developing unit from a toner cartridge, an image forming apparatus having the same and a toner path opening and closing method thereof.
2. Description of the Related Art
In general, a small image forming apparatus, such as a printer, has a developing unit in which a photoconductive medium and a toner containing part are integrally formed. However, a large image forming apparatus, such as a copier or a large printer, is configured with a developing unit having a photoconductive medium, such as an OPC drum, disposed therein and a toner cartridge containing a toner formed apart from the developing unit. In these large image forming apparatuses, the developing unit is often designed to be detached from the image forming apparatus, and another one put in its place.
FIGS. 1 and 2 are schematic prior art views of parts of a large image forming device exemplifying a developing unit detachably disposed from a main body and a toner supplying pipeline provided on part of the main body. A toner supplying pipeline 2 to which a toner cartridge (not illustrated) is connected is disposed in the main body 1 of the image forming device. The toner supplying pipeline 2 is opened and closed by a first shutter 3. A first sponge 4 is interposed between the toner supplying pipeline 2 and the first shutter 3. The first shutter 3 is elastically supported by a first elastic member 5, so that if an external force is not applied, it can close down the toner supplying pipeline 2.
A toner injecting port 11 is disposed in a developing unit 10, and the developing unit 10 is connected to the toner supplying pipeline 2. The toner injecting port 11 is opened and closed by a second shutter 12. A second sponge 14 is interposed between the toner injecting port 11 and the second shutter 12. The second shutter 12 is elastically supported by a second elastic member 15, so that if an external force is not applied, it can close down the toner injecting port 11.
FIGS. 3A through 3F are schematic views exemplifying prior art designs by which the toner supplying pipeline 2 and the toner injecting port 11 are connected to each other as the developing unit is mounted in the main body 1. In FIGS. 3A and 3B, when the developing unit 10 is mounted in the main body 1, an end tip of the developing unit 10 pushes a first shutter protrusion 3a projecting from the first shutter 3 to push and open the first shutter 3 in the direction of arrow A illustrated in FIG. 3A, and another end of the developing unit mount provided in the main body 1 pushes a second shutter protrusion 12a projecting from the second shutter 12 to push and open the second shutter 12 in the direction of arrow B illustrated in FIG. 3A.
Then, as illustrated in FIGS. 3C and 3D, a portion of the first sponge 4 where the first shutter 3 is opened and a portion of the second sponge 14 where the second shutter 12 is opened are pushed together and engage with each other to form a toner path. When the toner supplying pipeline 2 and the toner injecting port 11 are simultaneously opened and therefore communicate with each other by way of the toner path, toner in the toner supplying pipeline 2 begins to flow through the toner injecting port 11.
When the toner supplying pipeline 2 and the toner injecting port 11 are opened as described above and the first and the second shutter 3 and 12 are in a fully open state, the toner supplying pipeline 2 and the toner injecting port 11 are completely connected with each other, as illustrated in FIGS. 3E and 3F. However, when the toner supplying pipeline 2 and the toner injecting port 11 simultaneously start opening as described above, there is a period of time where the toner supplying pipeline 2 and the toner injecting port 11 do not coincide with each other while the first and the second shutter 3 and 12 are opened. That is, when the toner supplying pipeline 2 and the toner injecting port 11 start opening, toner that is injected through the portion of the toner supplying pipeline 2 hatched in FIG. 4A is not supplied to the developing unit 10 through the open portion of the toner injecting port 11 hatched in FIG. 4B. As a result, the portion or section of the toner pipeline 2 that is shaded in FIG. 4C is contaminated.
If the developing unit is repeatedly mounted and dismounted, toner accumulates in this section of the toner pipeline 2, and the toner in the contaminated section is spreads in the toner injecting port as a result of opening and closing of the second shutter 12. As the amount of toner that accumulates in the contaminated section increases as described above, the accumulated toner scatters and contaminates the inside of the image forming device, thereby resulting in image contamination and malfunction of the image forming device.